This BK Precision power supply came across my bench with a simple problem: the “jog dial” adjustment knob was operating intermittently. I was able to get it working again by replacing the defective rotary encoder with a new Bourns PEC12R-4220F-N0024 encoder.
Getting to the Encoder
Opening up the BK 1697 is fairly easy (remove the 3 PH2 phillips screws on each side of the case, then lift the case straight up), but getting to the rotary encoder requires a few additional steps. First, remove the 3 PH2 screws holding the front panel in place, then disconnect 5 connectors (see below). Some of the connectors may be glued in place, which requires a bit of prodding, prying, and/or cutting.
Once those connectors are removed, the front panel can be carefully rotated, allowing access to the 7 PH2 screws which hold down the main front panel PCB.
Once those screws are removed, the rotary encoder can be fully exposed.
Replacing the Encoder
I tried removing the encoder non-destructively as well as destructively. Both approaches were successful, but I found it difficult to heat up all 5 legs evenly enough to remove them together. The destructive method was much easier: using cutters, snip each of the 5 legs of the old encoder to remove it, then desolder each leg individually. At this point, clean up each through-hole pad so the new component can be soldered on.
Now, solder the new PEC12R-4220F-N0024 encoder into place, making sure to place it on the correct side of the board.
Closing up the Supply
Reassemble the supply by reattaching the front panel PCB back to the plastic panel, then reconnecting all the connectors, and finally screwing the remaining fasteners back. While reassembling, make sure to fold the gray display ribbon cable properly over the front panel PCB (see the PCB fasteners image above).
Final Results
